A standard mixing-valve faucet fixture has a housing containing a valve cartridge and mounted on a deck. Hot- and cold-water inlet pipes extend through the deck into the housing where they are connected to the cartridge and an outlet pipe extends from the cartridge to a faucet, or to a hose connected to a spray head that may form the end of a faucet. A handle on the housing operates the cartridge to control the mix of hot and cold water fed from the inlet pipes to the outlet pipe as well as the flow volume.
Normally the cartridge is secured as described in German patent document 3,120,210 of Gottwald and Koster by means of screws whose heads are visible on the outside of the housing. Not only is this type of installation unattractive, but the heads are subject to fouling and corrosion so that subsequent removal and replacement of the cartridge can be problematic.